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Current “Non-evaporable getters” (NEGs) are important for the improvement of vacuum by the help of metallic surface sorption of residual gas molecules. High porosity alloys or powder mixtures of Zr, Ti, Al, V, Fe and other metals are the base material for this kind of gas sorbents. The development of vacuum technologies creates new challenges for the field of getter materials. The main sorption parameters of the current NEGs, namely, pumping speed and sorption capacity, have reached certain level limits. Chemically active metals are the basis of NEGs of a new generation. The appearance of new materials with high sorption capacity at room temperature is a long-felt need. It is obvious, that chemically active metals and alloys with reactivity higher, than that of transition metals, can become this kind of materials. The potential of active metals as the strongest gas sorbents is very high. The improved getter materials allow faster pumping speed. The sticking rate on the chemically active surface is significantly higher, and sorption capacity can be increased by up to 104 times (during the life-time of a device the entire getter material reacts with residual gases). The main structural form of the new getter concepts are spherical powders, granules and porous multi-layers. The full pumping performance takes already place at room temperature and the activation temperature can be adjusted between room temperature and 660 °C. The successful insertion of this new chemical getter pump in a mobile double-walled LH2 tank system shows the very high sorption capacity of all relevant residual gases including H2. This new invention opens the possibility for significant vacuum improvements especially in the field of H2 pumping, which is an important challenge in many different vacuum devices and processes. 相似文献
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The paper addresses the problem of MOX-fuel self-protection at the “Spent Fuel Standard” level and more during full cycle of MOX-fuel management. Under conditions of the closed LWR cycle the proliferation-resistance levels were evaluated for fresh and spent MOX-fuel doped with 231Pa and 232U. According to the evaluations, it was derived that cyclic regime with Pa-U feeding at the level of 5% HM makes it possible to achieve the proliferation resistance of fresh MOX-fuel at the level high enough to protect it against short-term unauthorized actions (receiving the lethal dose for about 10 minutes in the vicinity of MOX-fuel assembly) and also against the acts of terrorism (receiving the shock lethal dose for a few minutes). 相似文献
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Graham Manton Robert M. Endsor Michael Hammond 《Propellants, Explosives, Pyrotechnics》2014,39(2):299-308
A major issue associated with munitions containing red phosphorus is that, during storage, red phosphorus can react, in the presence of moisture and air, to form a mixture of corrosive phosphorus acids and the toxic gas phosphine. This has raised serious concerns relating to the health and safety of personnel handling these munitions. This paper details the studies undertaken to assess the suitability of a chemically impregnated activated carbon cloth (phosphine getter material – PGM) for the static adsorption of phosphine evolved from munitions containing red phosphorus and its effective mitigation of phosphine present in both ammunition container assemblies and within the main body of munitions of this type. Laboratory assessment of PGM was undertaken along with real‐life ammunition container assembly trials covering several munitions containing red phosphorus and accelerated ageing trials using modified countermeasure cartridges. Reaction products formed from the reaction of phosphine with chemical impregnates were studied using scanning electron microscopy (SEM) and energy dispersive X‐ray analysis (EDX). Aqueous extraction of the phosphine reacted PGM confirmed the presence of the acidic species orthophosphoric acid (H3PO4) and phosphorus acid (H3PO3). 相似文献
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The electron stimulated desorption (ESD) was studied for quaternary Ti-Zr-Hf-V alloy coated stainless steel samples with different surface structures: dense on one sample and columnar on another. The ESD yields were measured as a function of electron accumulated dose up to ∼1023 e−/m2 or greater and three different NEG coating activation temperatures: 150, 180 and 250 °C. After each ESD experiment the samples were saturated with a mixture of H2, CO and CO2. Both samples depicted lower ESD yields for all desorbed species compared to a ternary Ti-Zr-V alloy. It was also shown that although the columnar NEG coating demonstrated better pumping properties and, for NEG activated at 150 °C, lower initial ESD yields, the higher activation temperature may result in a significant H2 yield increase with dose for the columnar NEG coating. This effect was demonstrated for the first time and should be considered for application in particle accelerators. 相似文献
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采用独立设计组装的磁控溅射装置完成了对不锈钢管道的镀TiZrV薄膜处理。对TiZrV薄膜的相关性能包括二次电子产额(SEY)、光致解吸(PSD)产额和吸气性能进行了研究。在200℃下加热2h后TiZrV的SEY有所下降,峰值由2.03降到1.55。不锈钢真空室在镀TiZrV薄膜处理后其PSD效应显著降低,在200℃下加热24h后,各气体的PSD产额与初始值相比可降低两个量级左右。TiZrV薄膜对CO和H2有较好的吸气效果,相同激活条件下对CO的抽速比H2高一个量级,吸气容量则较之低两个量级;另外,随着加热温度的提高和时间的延长,其吸气能力会有所提高。 相似文献